U.S. Pat. No. 3,960,789, Canadian Patent No. 1,032,679, and Japanese Patent No. 1,209,243 disclose paint binders comprising film-forming polycarboxy compounds, water-soluble upon neutralization, and water-insoluble polyhydroxy compounds based on polyesters, polyurethanes, or copolymers. These paint binders, as a principal feature, do not show the anomal behavior on dilution with water as do similar resins which are rendered water-dilutable on salt formation.
U.S. Pat. No. 4,431,780 and Canadian Patent No. 1,182,232 disclose a modification of the paint binders of U.S. Pat. No. 3,960,789 through a specific selection of the essential characteristics of the PC-component and PH-components. The binders thus obtained can be used for the formulation of air-drying paints.
The aforesaid paint binders can be formulated into paints for conventional applications despite the low content of auxiliary organic solvents in the paints. The films obtained afford excellent decorative properties. However, the corrosion protection of stoving primers and a single coat of the paints do not satisfy the rising exigencies of certain applications, such as in painting automobile bodies, particularly if the paint formulation does not include additional anticorrosive pigments.